1. Field of the Invention
The present invention relates to a method and apparatus for attaching time series music metadata.
2. Description of the Related Art
Audio reproducing apparatuses employing a large-capacity storage medium such as a semiconductor memory or a hard disk are currently in widespread use. More and more users are now storing and enjoying a vast amount of music data stored on not only an audio reproducing apparatus but also on a storage unit in an information device such as a personal computer or a cellular phone. Albums may be managed on removable recording media such as a compact disk (CD) or tape on a per medium basis, while a vast amount of music data for several hundreds to tens of thousands of songs can be handled on a single device.
Random accessing to a large amount of songs is possible without replacing a medium, and users can produce a playlist of songs across albums. Metadata attaching service system currently draws attention to efficiently search for a song among numerous songs and to group songs. The metadata attaching service system acquires music metadata, such as song title, artist name, album name, etc. from a database and then attaches the music metadata to music data. The metadata attaching service system acquires not only song titles, and artist names but also genre of each song and to some degree, tempo information.
The metadata attaching service system is basically developed to search for songs and to group songs, and actually used for searching and grouping purposes. The manner of listening to a song reproduced as a result of search remains unchanged from the known manner.
Tools are available for professional or semi-professional music creators who may compose and arrange songs. Such tools manage the tempo and beat position of a song in time axis, and edit music data with reference to the position. Similarly, some of available disk jockey software programs store position information of beats to superimpose a plurality of songs in synchronization with the beat.
Information regarding such beats is based on the premise that tempo remains unchanged throughout one song. In commercially available recorded content, tempo typically fluctuates in several localized portions of each song, and it is usually difficult to keep track of accurate beat positions.
If an apparatus automatically recognizes timing of bars and beats of music from live music waveforms, metadata of the beat position is acquired from a vast amount of music content recorded on an existing CD, and possibility is opened to a new entertainment.
Attempts have been made to automatically extract temp or beat.
For example, Japanese Unexamined Patent Application Publication No. 2002-116754 discloses one extraction method. In accordance with the disclosed method, autocorrelation of a music waveform signal is calculated as a time-series signal, beat structure of music is analyzed based on the calculated autocorrelation, and the tempo of the music is then extracted from the resulting beat structure.
In accordance with Japanese Patent No. 3066528, sound pressure data of each of a plurality of frequency bands is produced from music data, a frequency band that predominantly provides rhythm is identified from the plurality of frequency bands, and a rhythm component is then estimated from a variation period in the pressure data of the identified frequency band.